In the field of liquid crystal display technologies, within an In-Plane Switching display panel which is different from a Twisted Nematic (TN) display panel where liquid crystal molecules are arranged vertically, a planar electric field is generated between electrodes of pixels in the same plane so that alignment liquid crystal molecules between the electrodes and those right over the electrodes can be rotated to a direction parallel to the plane of the substrate, thereby improving light transmittance of a liquid crystal layer. Moreover, if the liquid crystal molecules are subjected to an ambient pressure, the liquid crystal molecules slightly sink downward but are almost still maintained in the same plane overall, and hence images displayed by the display panel will not suffer from distortion and color degradation, thereby preventing the effect of the displayed images from being impaired. Due to its advantages such as a fast response speed, a large viewable angle, ripple-free touch, and real color presentation, the In-Plane Switching display panel has been widely applied in various fields.
As shown in FIG. 1, a pixel unit of an conventional In-Plane Switching display panel includes a common electrode 101 and a pixel electrode 102 which are disposed over one another, and an insulation layer (not shown) disposed between the common electrode 101 and the pixel electrode 102, where the common electrode 101 has a plurality of strip branch electrodes 103 and an end electrode 104 disposed at ends of the branch electrodes 103. When a voltage is applied across the common electrode 101 and the pixel electrode 102, a planar electric field can be formed between the common electrode 101 and the pixel electrode 102 to control rotation of the liquid crystal molecules.
FIG. 2 is a partially enlarged view showing arrangement of liquid crystal molecules of the pixel unit at a position a shown in FIG. 1. With reference to FIG. 2 in combination with FIG. 1, a first electric field E1 with a direction X is formed between the pixel electrode 102 and the branch electrode 103 of the common electrode 101, so that the liquid crystal molecules 100a are rotated, under the effect of the first electric field E1, from the initial alignment directions (i.e. directions of macro-axes of liquid crystal molecules represented by solid lines) to a direction parallel to the direction of the first electric field E1. However, the liquid crystal molecules 100b close to the end electrode 104 of the common electrode will be subjected to the control of second electric fields E2. Also, such second electric fields E2 close to the end electrode 104 have different directions, so that the liquid crystal molecules 100b have different rotation directions when they are rotated from the respective initial alignment directions to directions parallel to the directions of the second electric fields E2 under the effect of the second electric fields E2 having different directions. As shown in FIG. 2, for example, the liquid crystal molecule 100b-1 is rotated to the right, but the liquid crystal molecule 100b-2 is rotated to the left. Furthermore, since the liquid crystal molecules close to the end electrode 104 of the common electrode will also be affected by the first electric field E1 in addition to the second electric fields E2, arrangement of these liquid crystal molecules may be further disordered and hence form black disclination lines at edge positions of the pixel unit. In this case, if an external force is applied to a surface of the display panel and a slide operation is performed on the surface, the arrangement of the liquid crystal molecules is more disordered, resulting in an increase of a black disclination line region at the edge positions of the pixel unit, a decrease of light transmittance of the pixel unit and a reduction of luminance of the pixel unit, leading to nonuniform display and trace Mura in the display panel.